🔐 Can you crack your way into this corporate admin portal?

Client-side authentication occurs when password validation logic is implemented in JavaScript that runs in the user's browser. This approach is fundamentally insecure because attackers have complete access to the authentication code, can modify it at runtime, and can extract any stored credentials or hashes. Combined with weak hashing algorithms like MD5, this creates easily exploitable vulnerabilities.

1. Access the portal: Navigate to the TechFlow Solutions administrative portal
2. Examine the interface: Observe the professional corporate login form
3. Test basic credentials: Try common passwords like 'admin', 'password', '123456' to confirm they don't work
4. Open Developer Tools: Press F12 or right-click and select 'Inspect Element'

1. View page source: Right-click and select 'View Page Source' or press Ctrl+U
2. Locate JavaScript section: Scroll down to find the <script> tag containing the authentication logic
3. Identify key variables: Look for suspicious variables or hash values

// Found in the JavaScript code:
const adminHash = "73f00c3c413525d5aa70c7914913ddc6";

4. Analyze the validation function: Examine the validateLogin() function

// The validation logic:
if (md5(password) === adminHash) {
    // Success - redirect to flag
    window.location.href = `/${password}/flag.html`;
} else {
    // Failure message
}

5. Understand the flow: The system hashes the entered password with MD5 and compares it to the stored hash

Method 1: Online MD5 Reverse Lookup

1. Use online tools: Visit websites like HackerDNA MD5 Decrypt, md5decrypt.net, crackstation.net, or hashkiller.co.uk
2. Enter the hash: Input the hash 73f00c3c413525d5aa70c7914913ddc6
3. Get the result: The tools should return the original password: 789456123789456123

Method 2: Command Line Tools

1. Using Hashcat:

# Create a hash file
echo "73f00c3c413525d5aa70c7914913ddc6" > hash.txt

# Crack with wordlist
hashcat -m 0 -a 0 hash.txt rockyou.txt

# Or try mask attack for numeric pattern
hashcat -m 0 -a 3 hash.txt ?d?d?d?d?d?d?d?d?d?d?d?d?d?d?d?d?d?d

2. Using John the Ripper:

# Create hash file in correct format
echo "admin:73f00c3c413525d5aa70c7914913ddc6" > hash.txt

# Crack with John
john --format=raw-md5 --wordlist=rockyou.txt hash.txt

# Show cracked passwords
john --show --format=raw-md5 hash.txt

Method 3: Python Script

#!/usr/bin/env python3
import hashlib

target_hash = "73f00c3c413525d5aa70c7914913ddc6"

# Try common admin passwords
passwords = ["admin", "password", "789456123789456123", "administrator", "123456789"]

for password in passwords:
    md5_hash = hashlib.md5(password.encode()).hexdigest()
    if md5_hash == target_hash:
        print(f"Password found: {password}")
        break

Method 4: Browser Console Testing

# Open browser console (F12) and test:
md5("789456123789456123")
# Should return: "73f00c3c413525d5aa70c7914913ddc6"

# Verify it matches the stored hash
adminHash
# Should return: "73f00c3c413525d5aa70c7914913ddc6"

1. Enter the cracked password: Go back to the login form and enter 789456123789456123
2. Submit the form: Click 'Access Portal' to authenticate
3. Observe the success message: The system displays 'Access granted! Redirecting to secure area...'
4. Automatic redirection: After 1.5 seconds, you're redirected to /789456123789456123/flag.html
5. Flag extraction: The secure page displays the challenge flag

Direct URL Access

1. Guess common passwords: Try accessing URLs like /admin/flag.html, /password/flag.html
2. Brute force directories: Use tools like dirb or gobuster to find accessible paths

JavaScript Manipulation

1. Modify validation logic: Change the adminHash variable in the console
2. Bypass validation: Directly call the success redirect code

# In browser console:
adminHash = md5("mypassword")
# Then enter "mypassword" in the form

# Or directly redirect:
window.location.href = "/789456123789456123/flag.html"

Network Analysis

1. Monitor network traffic: Use browser DevTools Network tab
2. Analyze requests: Look for any server-side validation endpoints
3. Check for additional resources: Look for other accessible files or directories

Why This Attack Succeeded

• Client-side validation: Authentication logic runs in the browser, giving attackers full access to the code
• Weak hashing: MD5 is cryptographically broken and vulnerable to rainbow table attacks
• Predictable password: '789456123789456123' follows common patterns and appears in password dictionaries
• Source code exposure: The hash is stored directly in the JavaScript code
• No server-side verification: No backend validation of credentials

Real-World Impact

• Administrative access: Attackers gain full administrative privileges
• Data exposure: Access to sensitive corporate information and user data
• System compromise: Potential for further lateral movement and privilege escalation
• Compliance violations: Breach of security standards and regulatory requirements

• Server-side authentication: Implement all authentication logic on the server side
• Strong hashing algorithms: Use bcrypt, scrypt, or Argon2 instead of MD5
• Secure password policies: Enforce complex passwords with sufficient entropy
• Multi-factor authentication: Add additional authentication factors beyond passwords
• Session management: Implement proper session tokens and timeout mechanisms
• Input validation: Validate all inputs on both client and server sides
• Security headers: Implement CSP, HSTS, and other security headers
• Regular security testing: Conduct penetration testing and code reviews

• Browser Developer Tools: Essential for analyzing client-side code and network traffic
• Online MD5 crackers: Quick and easy for common passwords in rainbow tables
• Hashcat: High-performance password cracking with GPU acceleration
• John the Ripper: Versatile password cracking tool with multiple attack modes
• Custom scripts: Python or other languages for targeted password testing
• Directory enumeration: Tools like dirb, gobuster, or dirbuster for path discovery

• Web application penetration testing: Identifying client-side authentication vulnerabilities
• Security code reviews: Analyzing JavaScript for security flaws
• Bug bounty hunting: Finding authentication bypasses in web applications
• Incident response: Understanding how attackers might have gained unauthorized access
• Security awareness training: Demonstrating the dangers of client-side security

This Admin Portal Breach challenge demonstrates the critical security vulnerabilities inherent in client-side authentication systems. By combining weak password hashing with client-side validation, the application creates easily exploitable attack vectors that allow unauthorized access to administrative functions. The challenge emphasizes the importance of proper authentication architecture, strong cryptographic practices, and the fundamental principle that security-critical operations must never be implemented solely on the client side.